Prior art mechanical power transmissions and drive systems typically incorporate a clutch mechanism for transmitting power between power transmitting, rotary shafts. These prior art systems have limited applications because of their inability to easily shift between different conditions. When used with machines, such as power lawn mowers, it is particularly desirable for the operator to easily shift between the various operating conditions such as forward, neutral, and reverse in an easy, quick, and precise manner. Also, considerable effort to improve the braking system is being expended by manufacturers of the small machines discussed herein. For reasons of economy, the low power systems associated with riding and walk behind lawn mowers and the like, typically use mechanical actuators to engage and disengage the power source from the power drive system, as well as to reverse direction of the output shaft from the transmission. However, these mechanical actuators are somewhat complicated to operate. Since these relatively small machines are operated by a wide range of people, including many with little or no experience in operating machines, a safe, easy to operate and relatively inexpensive actuating system is extremely important.